Takeaway Tek

created by: ks_cacti

Growing cacti from seeds can seem daunting to someone new to the fold. It can be simple if you follow this technique (Tek). It works on nearly all cactus seeds (there’s always someone who will find an exception), is simple, inexpensive, and can be very successful for new growers on a small scale.

Learn the rules like a pro, so you can break them like an artist.
- Pablo Picasso

You cannot improve what you do not understand.
- W. Edward Denning

You know nothing, Jon Snow.
- Ygritte, A Song of Ice and Fire, George R. R. Martin

Keep these sayings in mind as you read and follow this. On the Internet, you can find someone to tell you just about anything you want to hear. You will also find other write-ups called “Takeaway Tek” and wonder whether you can borrow one thing from one and something else from another. Well, you can, but until you know why, you have no idea what the outcome will be. Follow one set of instructions to the letter, then see whether you need or want to change anything after you see your results.

• Potting Soil
• Pumice (preferred) or Perlite
• Takeaway Container
• De-chlorinated Water
• 3% Peroxide (Optional)

Potting Soil: Avoid “Miracle-Gro”; people have reported issues with it for cacti. Fox Farms Happy Frog Potting Soil is known to work well.

Pumice or Perlite: Pumice between 1 and 4mm or similarly sized perlite. Even smaller is better. Pumice is the preferred choice; perlite will eventually float and separate from the rest of the soil. Wash this through a fine window screen or kitchen sieve to remove dust and micro-particles.

Takeaway Container: Anything here will work. Food prep containers with a clear top and a well-sealed lid, such as these 25oz Meal Prep Containers on Amazon (non-affiliate link) or similar options, will work. If you reuse actual takeout containers, wash them well with dish soap and rinse thoroughly.

De-chlorinated Water: Chlorine can be boiled out of water or even allowed to dissipate in an open container overnight. Most municipalities now use chloramine, which is much harder to remove. You can use tap water and an aquarium water conditioner to remove chlorine and chloramine, use spring water, drinking water, or even collected rainwater (but keep in mind rainwater will introduce potentially harmful microbes).

3% Hydrogen Peroxide: Hydrogen peroxide is a versatile tool for cacti, especially seedlings. It can be misted on seedlings at full strength to help control fungal infections and some pests, and can be added to your water at a 1:15 ratio of 3% H₂O₂ to water (1 tablespoon per cup) or at ¼ cup 3% H₂O₂ per 1 gallon of water. You will also soak your seeds in it to remove surface pathogens.

• ¼” Sieve
• Spray Bottle
• Microwave (optional)
• Seedling Heat Map (optional)
• T5 Grow Light (optional)

¼” Sieve: You will use this often when creating soil mixes. A ¼” sieve is suitable for removing bark from soil mixes and for selecting finer granular materials to mix into the soil. You can make one from #4 galvanized screening or purchase an inexpensive set from an online retailer.

Spray Bottle: You will use this for watering in your seeds, for spraying down any fungus, for watering the seedlings, and for several other things. A good sprayer with a fine mist is fine, but a fancy atomizing sprayer isn't needed. You want a little “weight” to the spray.

Microwave (optional): A microwave can be used to sanitize soil, if desired.

Seedling Heat Map (optional): Seedlings perform best between 75 and 85°F. A heat map can help the seedlings sprout and grow faster, but do not exceed 85 degrees.

T5 Grow Light (optional): Your seedlings will need light as they grow; an inexpensive T5 or a T5-sized LED grow light is fine.

Most potting soil contains decomposing sticks and bark. These are organic sponges and increase the risk of fungal growth, which can attack young seedlings. Use your sieve to remove these and any other chunks that are over ¼” in size. Then mix your pumice or perlite into the soil at a 50/50 soil-to-pumice/perlite ratio. If the soil is dry, adding a small amount of moisture will help keep it from separating and stratifying.

Do not use sand. Sand will compact and stunt your seedlings' growth.

Pour your prepared soil mix into the container, leaving it about ½” below the top. Add your water gently with your spray bottle. You are looking for what is called “field capacity”, which is soil that is fully saturated but with no excess. If you squeeze the soil and water pours out, it’s too wet. If you overdo it, it’s fine, just let the container settle and gently tip it to pour out the excess.

You may also use full-strength 3% peroxide to moisten the soil. Review the notes below about sanitation and sterilization before performing this step.

Sterilization is the destruction of all living microorganisms, including fungal spores and bacteria. It requires 180 °C (356 °F) for 30 minutes (dry soil and minerals), or 121 °C (250 °F) at 15 psi for 15–30 minutes (e.g., a pressure cooker). If you choose to limit microorganisms in your soil, actual sterilization can release ammonia and significantly change soil chemistry. Since you are trying to give your seedlings a good start, this is not recommended. Sanitization is the preferred approach to limit microorganisms.

You can sanitize your moistened soil by closing your takeout container and microwaving it for about four minutes. Leave it covered and let it cool for an hour or so.

Many people do not worry about the microorganisms in the soil. Indeed, many are beneficial, and there is an argument that removing all of them can create an environment in which the eventual introduction of pathogens can overwhelm the soil and destroy your seedlings. This is not dissimilar to the microorganisms in your gut. Taking antibiotics can sometimes have “undesirable” effects. Some potting soil companies such as Fox Farms advertise that they add beneficial microorganisms, and many people even inoculate their soils with Mycorrhizae. This beneficial fungus can work synergistically with your plants.

For this Tek, assuming good-quality soil, sanitization is not necessary. Be mindful, though. Often, soil from garden centers, even from a reputable brand, can contain fungus gnat eggs. These larvae can attack your seedlings, and the nuisance of gnats in your home can become very frustrating. You can use Bacillus thuringiensis israelensis to kill the larvae while preserving your soil's beneficial microbes. This is available as “Mosquito Bits” or as a prepared solution. It does not work instantly; you need to apply it to your potting soil weekly for 2-3 weeks.

The least disruptive way to prevent releasing clouds of fungus gnats into your home is to pour the soil into a bucket and tightly seal it for about a week. After that, open the bucket outside and check if any gnats fly out or if there are dead ones on the soil surface. If there are any, you'll need to address them. If not, you can probably proceed without any issues.

If you are reading this, you probably want to start now and not in weeks. You have enough information to make a decision that works for you. I can say most experienced growers either use their own soil mixes or buy good soil from a good supplier and use it as intended.

Soaking cactus seeds in a diluted hydrogen peroxide solution is a typical method used to reduce surface pathogens and improve hydration before sowing. The peroxide helps break down fungal spores, bacteria, and debris on the seed coat, lowering the chance of contamination during germination. It also slightly softens the outer seed surface, allowing water to penetrate more effectively.

You can choose not to soak in peroxide. Still, the seeds are a significant source of microbes from a different environment, and they could impact your environment differently than they would in their original habitat.

Soak your seeds in 3% hydrogen peroxide or water (your choice) for 1–3 hours, then blot them dry on a paper towel until they are sufficiently dry to handle.

Sprinkle your seeds evenly over your container. If you are using one of the containers recommended, about 50 seeds is probably as many as you will want to sow. They are challenging to distribute evenly, so sprinkling them over the soil as you would salt on your food is as easy and effective as anything else.

Once the seeds are distributed over the surface, use your spray bottle again to add moisture to the top and lightly settle them into the surface. Do not bury the seeds.

The container should receive consistent light and adequate warmth. One practical method is to place the container on a seedling heat mat and use a grow light, such as a T5 LED. If you prefer not to use a heat mat, it is best to sow the seeds in late spring or summer when ambient temperatures are higher, as cold soil can prevent germination. If a grow light is not available, a bright windowsill or an outdoor location with indirect light can also work. When there is a possibility of direct sun, cover the container with shade cloth or another light-filtering material to prevent heat and light stress on young seedlings.

When the soil remains moist, the light is consistent, and the temperature stays warm enough, germination typically begins within 7–14 days. Seeds may germinate slightly sooner when both a heat mat and a grow light are used. Most seedlings will appear within the first month, although some may emerge later.

The only thing to watch out for is fungal growth and algae covering your seedlings. If you see any, misting with peroxide will eliminate it.

Between about 12 and 16 weeks, you can begin acclimating the seedlings to open air, a process sometimes called “hardening”. This is done by removing and replacing the lids, gradually increasing the duration of container exposure over one to two weeks. For example, start with 5 minutes on the first day, then increase to 10 minutes the next day, 15 minutes the following day, and continue extending the duration to 30 minutes, 1 hour, and eventually longer intervals until the lid can remain off entirely.

During the early stages, monitor the soil closely and mist with clean water if it begins to dry out. Once the lid is entirely removed, allow the soil to dry slightly between waterings.

After about six months, you'll want to re-pot your seedlings individually or in small groups. Be gentle to avoid tearing the delicate roots. There's a balance between letting them grow until they are ready and allowing them to grow so much that their roots become tightly intertwined. If the seedlings are 2-3 inches tall, you can use running water to help separate the roots.

At this point, use high-quality cactus soil, which is a topic for another article.